随着大模场光纤的出现，光纤激光器输出的能量得到很大的提高，大能量脉冲光纤激光器在工业加工，医疗以及深空激光通信等领域有着广泛的应用。　　　论文首先研究了宽光谱瞬态脉冲光纤放大器的放大理论模型，并对其进行了数值计算。分析了光纤参数，包括光纤长度、芯径，种子参数以及泵浦参数，以及泵浦宽度，泵浦峰值功率等因素对光纤激光特性的影响。所得结果有助于理解宽光谱脉冲泵浦光纤放大器的动态特性，相关结果可用于光纤放大器的设计和优化。　　　通过建立光波导的波动方程，利用有限差分BPM算法研究了高峰值功率脉冲光波导中的传播规律。计算了在接近以及达到波导自聚焦阈值的时候，光脉冲模场沿着波导传播的变化规律，计算的结果有利于深刻理解高能量高峰值功率脉冲在波导中传播的物理过程。提出了利用增益补偿以及折射率补偿来抑制自聚焦阈值的方法，并且计算了在不同折射率补偿形状下的峰值功率高于自聚焦阈值的脉冲的传播规律。同时对光纤激光器中的模式匹配以及不同波长下的模式分布以及光束质量进行了研究。　　　摸索了大能量脉冲光纤激光器所涉及的一些至关重要的关键技术。分析了脉冲光纤放大器储能极限以及可提取能量；分析了脉冲放大过程中的脉冲畸变规律；分析了多级放大噪声抑制的方法；分析了脉冲光纤系统中的非线性现象，计算了在不同参数下的SBS和SRS阈值。基于激光约束核聚变对光纤激光器的要求，研究了大能量高峰值功率脉冲光纤激光器。在主控振荡器的功率放大器基础理论的指导下，总体技术方案设计为SLD为种子以大模场光纤做为主放光纤的能量扩展结构，解决了SBS对输出能量的限制，采用多级同步脉冲泵浦方法解决了低重频光纤激光器输出ASE严重的问题。基于全光纤化的关键技术实现了30 mJ 3 MW全光纤化脉冲激光器，同时实现了60 mJ 5 MW分立脉冲激光器，实验结果说明了结构设计的合理性和技术方法的可靠性。分别从理论分析层面和工程技术层面解决了能量几十毫焦级峰值功率MW级脉冲光纤激光器所面临的一系列问题，并实现了预期的各项指标。同时研究结果为发展更高能量和峰值功率输出的脉冲光纤激光器奠定了基础。

　　　Due to the appearance of large mode area fiber, the energy of fiber laser has been improved a lot which has been applied in industrial processing, medicine and deep optical communication. Mean while , it has the advantage of easy thermal management，stable mechanical properties and freeness of complex assembly etc.Thus, high energy fiber laser have received a significant attention all around the world over the last decade.　　　Due to the appearance of large mode area fiber, the energy of fiber laser has been improved a lot which has nearly been approaching 100 mJ. Mean while , it has the advantage of easy thermal management，stable mechanical properties and freeness of complex assembly etc.Thus, high energy fiber laser have received a significant attention all around the world over the last decade.　　　Through the establishment of wave equation of waveguide, the propagation characteristics of high peak power pulse has been analyzed with the BPM algorithm. the propagation law of pulse with peak power approaching self-focus threshold has been computed which could be helpful of understanding of the propagation of high energy and peak power pulse. 　　　The method to prevent the self-focus has been proposed with the usage of gain compensation and refractive index compensation. The propagation law of pulse with the peak power of self-focus in different compensation conditions has been computed which has verified the feasibility of the theory.　　　The key technology of high energy fiber laser has been investigated.the analysis of energy storage limit and extractable energy could determine the parameters of fiber; the law of pulse deformation has been studied. The pre-compensation method has been proposed to solve this issue.the noise of this system has been studied and many methods such as time-domain filter, frequency-domain filter and pulse pump technology have been applied to suppress ASE to improve the signal-noise-ratio and energy; the SBS characteristics has been studied and the threshold in different conditions have been computed. And the method with the SLD as the seed have been proposed to increase the SBS threshold; the fiber damage mechanism and threshold have been studied and the feasibility of the energy has been computed.　　　Based on the requirements of laser-confinement fusion, the high energy and peak power pulsed fiber laser has been investigated. With the guidance of MOPA theory, the structure with the SLD as seed and large mode area fiber as gain medium has been designed and built which has solved the issue of SBS and ASE with the method of synchronized pulse pump. And the 30 mJ 3 MW all-fiber amplifier and 60 mJ 5 MW separated structure fiber amplifier has been realized which could verify the rationality of the structure and reliability of the technical method.　　　 From theoretical and practical perspectives, a series of issues during studying tens of mJ pulsed fiber laser are solved while the expected specifications are all completed. The research results have laid the foundations for the development of monolithic fiber laser with higher energy and peak power output.